13 -- Somatosensory systems part 2

13 -- Somatosensory systems part 2 - Somatosensory System...

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Somatosensory System PAIN     feeling/perception  of unpleasant or unbearable sensations Is  NOT NOT  result of excessive stimulation of other somatosensory systems Depends on specifically dedicated receptors and pathways NOCICEPTION     sensory processes  (receptor activation, signal transduction)       that lead to the conscious perception of pain * Note to class:  Pain as defined on a test is NOT “sitting through yet another neurobiology lecture” * Note to class:  Pain as defined on a test is NOT “sitting through yet another neurobiology lecture”
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Somatosensory System PAIN mediated by  NOCICEPTORS NOCICEPTORS Sensory neurons that have bare dendritic nerve endings  [ diff. from touch ] Pathway through spinal cord to brain also different than touch
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NOCICEPTORS    2 main categories based on axonal properties A-Delta (A A-Delta (A δ ) Fast, sharp, “prickling” pain (also known as “first” pain) Somatosensory System has membrane channels in terminals that respond to dangerous (“noxious”) mechanical & thermal stimuli medium-sized diameter and some myelination (5-30 m/sec) * The opposite of noxious is “innocuous” harmless
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NOCICEPTORS    2 main categories based on axonal properties A-Delta (A A-Delta (A δ ) Mechanonociceptors    respond selectively to strong, harmful mechanical insults (tissue puncture,  tearing, etc.) Thermonociceptors    respond selectively to extreme heat (>52°C) and to extreme cold (<17°C) Membrane of dendritic branches have specialized ion channels called  TRPV2 TRPV2  channels than  open at extremely hot/cold temps and cause depolarization Somatosensory System has membrane channels in terminals that respond to dangerous (“noxious”) mechanical & thermal stimuli medium-sized diameter and some myelination (5-30 m/sec)
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This note was uploaded on 03/23/2009 for the course BIOL 450 taught by Professor Jeremyingraham during the Spring '09 term at UNC.

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13 -- Somatosensory systems part 2 - Somatosensory System...

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